Relationship between ultrasonographic, electromyographic, and clinical parameters in adult stroke patients with spastic equinus: an observational study.

OBJECTIVE: To find more accurate indices that could affect decisions in spasticity treatment by investigating the relation between ultrasonographic, electromyographic, and clinical parameters of the gastrocnemius muscle in adults with spastic equinus after stroke. DESIGN: Observational study. SETTING: University hospitals. PARTICIPANTS: Chronic patients with stroke with spastic equinus (N=43). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Ultrasonographic features were spastic gastrocnemius muscle echo intensity, muscle thickness, and posterior pennation angle of the gastrocnemius medialis (GM) and gastrocnemius lateralis (GL) in both legs. Electromyographic evaluation included compound muscle action potentials (CMAPs) recorded from the GM and GL of both legs. Clinical assessment of the spastic gastrocnemius muscle was performed with the Modified Ashworth Scale (MAS) and by measuring ankle dorsiflexion passive range of motion (PROM). RESULTS: Spastic muscle echo intensity was inversely associated with proximal (GM and GL: P=.002) and distal (GM and GL: P=.001) muscle thickness, pennation angle (GM: P< .001; GL: P=.01), CMAP (GM: P=.014; GL: P=.026), and ankle PROM (GM: P=.038; GL: P=.024). The pennation angle was directly associated with the proximal (GM and GL: P< .001) and distal (GM: P=.001; GL: P< .001) muscle thickness of the spastic gastrocnemius muscle. The MAS score was directly associated with muscle echo intensity (GM: P=.039; GL: P=.027) and inversely related to the pennation angle (GM and GL: P=.001) and proximal (GM: P=.016; GL: P=.009) and distal (GL: P=.006) muscle thickness of the spastic gastrocnemius. CONCLUSIONS: Increased spastic muscle echo intensity was associated with reduced muscle thickness, posterior pennation angle, and CMAP amplitude in the gastrocnemius muscle. Building on previous evidence that these instrumental features are related to botulinum toxin response, these new findings may usefully inform spasticity treatment decisions.